1. Field of the Invention
The invention relates to a method and a system for detecting the bandwidth of a signal transmitted by a transmitter, in particular, a mobile-radio device, especially for the LTE (Long Term Evolution) standard for fourth-generation mobile telephones.
2. Related Technology
Conventionally, in radio communications systems, one channel or a plurality of channels is/are allocated to mobile subscribers by a base station. The mobile subscriber can use exclusively this channel or these channels. If the mobile subscriber leaves the channel or the channels allocated to him, for example, by transmitting with a larger bandwidth, transmissions disposed in the adjacent frequency range are disturbed. This occurs if the mobile subscriber has either received the channel allocation incorrectly or is not responding correctly to the channel allocation. Such difficulties are normally not resolved specifically. Accordingly, a check on the channel allocation or a reallocation is implemented only when transmission difficulties are encountered, for example, through a lack of synchronization of the subscriber and the base station. An investigation of the bandwidth actually transmitted from the mobile subscriber is not implemented in this case. Accordingly, the base station determines that the mobile subscriber is transmitting with an incorrect bandwidth only after running through several unsuccessful reception procedures. The efficiency of the transmission is reduced as a result.
For instance, the patent application GB 2 434 279 A discloses a method for the allocation of resources to individual subscribers within a communications system. However, a monitoring of the observance of these allocated resources is not disclosed. The German published application DE 103 37 828 A1 discloses a method for selecting a transmission channel, on which a mobile user device transmits messages to a base station. Here also, a monitoring of the observance of the selected channel does not take place.